Qt4 Hildon Legacy

2009-07-02T07:07:06Z

192.100.124.220: /* Introduction to Git */

Qt4 Hildon Legacy

2009-07-02T07:05:51Z

192.100.124.220: /* Merging branches changes in the mainline [OLD] */

Qt4 Hildon Legacy

2009-07-02T07:04:56Z

192.100.124.220: /* Building Qt from GIT rep */

2009-06-29T11:03:07Z

192.100.124.220: /* Maemo fixes */

The Maemo version of Qt lives here:
http://gitorious.org/+qt-maemo-developers/qt/qt-maemo

If you have a local clone you can use <code>gitk --all</code> to see a visual representation of the branches, commits and merges.

lbt proposed this explanation of the branches/workflow based on the [[Mer/Build/UsingGitorious|Mer gitorious workflow]]

== Origin ==
The branches are synced with upstream Qt changes. No Maemo changes are there at all.
=== master ===
represents the latest core Qt master branch (currently 4.6)
=== 4.5 ===
represents the latest core Qt branch for 4.5

== Maemo master branches ==
Currently we have 4.5 master branch only.

=== master-maemo-qt-45 ===
This branch is based on 4.5 and has all feature branches selected for maemo merged into it.
Note that this branch is fairly plain Qt and should contains no packaging data and debian/* should not exist.

If an updates is made to 4.5 and 4.5 is merged into master-maemo-qt-4.5 then *all* conflicts with all feature/bug branches will be seen at once.
To avoid this, 4.5 is merged into each bug/feature branch and conflicts resolved in focused feature areas.
Now we need to merge the conflict-resolved features into master-maemo-qt-4.5.
At this point it may seem reasonable to simply re-merge each feature branch into master-maemo-qt-4.5 however master-maemo-qt-4.5 contains all the other features from the last merge. So as soon as the first conflict-resolved feature is merged, all the conflicts from all the other features will be hit.
The answer is to create a temporary local branch based on the latest 4.5 (see http://wiki.maemo.org/Mer/Build/UsingGitorious#Upstream_Updates) and merge each feature in turn into this branch. Then merge that into master-maemo-qt-4.5 (which should have no conflicts at all and, in the absence of any features/bugs is a simple fast-forward).

== Maemo build branches ==
These branch should be built completely and used for regular release. There are based on master-maemo-qt-45 currently.

=== qt-diablo ===
Diablo branch

=== qt-fremantle ===
Fremantle branch, but this is not ready yet.

=== qt-mer ===
Currently there is no branch.

== Maemo build script and debian folder ==
=== maemo-build-generic ===
This branch is based on and tracks ??(I suggest master-maemo-qt-4.5)
It contains common packaging (ie debian/*) that allows Qt to build on various maemo-ish releases.
A good rule is that no code is touched by non-merge commits to this branch
It simply merges master-maemo-qt-4.5

=== maemo-build-diablo ===
Branched from maemo-build-generic and modified with packaging/configuration specifically used for diablo
Note that maemo-build-diablo is not merged back

=== maemo-build-fremantle ===
Branched from maemo-build-generic and modified with packaging/configuration specifically used for fremantle

=== maemo-build-mer ===
Branched from maemo-build-generic and modified with packaging/configuration specifically used for Mer

=== maemo-qt-scripts ===
There are some scripts to manage maemo branches or create release pacakge etc.

== Maemo fixes ==
These branches have each feature/ bug fix only. In the future, we will create a new maemo master branch, e.g. based on 4.6, at that time it is easy to chery-pick the modification to the new master branch.

=== bug-* ===
Representing potential bugs in Qt
These branches hold fixes to specific bugs.
The 4.5 branch will be merged into them to keep them up-to-date. If the bug is fixed upstream the branch will be deleted.

=== hildon-* ===
Each of these branches contain changes able to integrate Qt in the hildon environment. (Input method, menus, style).
TO FIX: Actually the widget-* branches shoul be renamed in hildon-widget-*

=== hw-* ===
Contain changes that improve the usability of Qt with touchscreen device.
Feature like right mouse button emulation, easy double click and so on.
TO FIX: Actually the ts-* branches should be renamed in hw-ts-*

=== maemo-* ===
Representing features in various areas and branched from cloned 4.5 branch.
Each branches adds only one feature-area.

The main covered areas are:
- maemo-build-*
- maemo-qt-scripts
- others maemo related areas.

[[Image:MaemoQtOnGit-Diagram-opt2.jpg]]

2009-03-20T14:04:58Z

192.100.124.220: /* Image:Helmet.png Maemo Qt API Reference */

[[Image:MaemoQtPicture.png]]
== [[Image:Intro.png]] Intro ==

=== Maemo Platform ===
The Maemo Platform is the software stack for Nokia Internet Tablets, which includes the Maemo operating system and the Maemo SDK. The Maemo Platform is mostly based on open source code, and has been developed by the Maemo Software department within Nokia in collaboration with many open source projects such as the Linux kernel, Debian, and GNOME.
(from [http://en.wikipedia.org/wiki/Maemo_Platform wikipedia])

[http://maemo.org/intro/platform/ Read more...]

=== What is Hildon? ===
Hildon is an application framework for Linux operating system mobile devices (PDAs, mobile phones, etc), developed by Nokia for Maemo and now a part of GNOME, that focuses on providing a finger friendly interface
[http://en.wikipedia.org/wiki/Hildon Read more]

=== Developing on Maemo ===
Developing applications for Maemo is done with the Maemo SDK. The process from creating the first prototype of your application to distributing to a wide audience consists basically of three steps:

* share your application project in the Maemo Garage
* make your application easy to install and put in the Application Catalog
* once your application has a high quality - be promoted to the Nokia user site
[http://maemo.org/intro/developer_overview/ Read more...]

=== Maemo SDK ===
(from [http://en.wikipedia.org/wiki/Maemo_Platform Wikipedia])
The Maemo SDK is based around the Debian-oriented Scratchbox Cross Compilation Toolkit, which provides a sandbox environment in which development may take place. Scratchbox uses Qemu to emulate an ARMEL processor or sbrsh to remotely execute instructions. Scratchbox-compatible rootstraps are available for both x86 and ARMEL, so the majority of development and debugging takes place on x86, with final packaging being for ARMEL.

[http://www.youtube.com/watch?v=c8myh_iBy8k Watch the Maemo SDK in action!]

=== What is Scratchbox? ===
Scratchbox is a cross compilation toolkit designed to make embedded Linux application development easier. It also provides a full set of tools to integrate and cross compile an entire Linux distribution.
[http://en.wikipedia.org/wiki/Scratchbox Read more...]

== [[Image:Rocket.png]] Getting started ==

To start to develop with Maemo Qt, we need to install the Maemo SDK in our linux box.

=== Hey, I don't have a linux box! ===
That's not a big problem. Maemo SDK Virtual Image project provides a programming environment for Maemo platform.
You can download from [http://maemovmware.garage.maemo.org/ here] the VMWare image that you can run in [http://www.vmware.com/products/player/ VMPlayer].

=== Installing the Maemo Scratchbox ===
If you want to install the maemo SDK on your linux box this is the page that you want to check:
[http://maemo.org/development/sdks/ SDK Releases]

=== Installing the Qt packages in Scratchbox ===
After Scratchbox and SDK are installed and working, you need to login, add the "extra" and "extra devel"
repositories to your apt-get sources and install the Qt libs. Here's how:

* Paste this into your Scratchbox shell (without the ">" prompt):
<pre>> echo "# Maemo extras and extras-devel
deb http://repository.maemo.org/extras/ diablo free non-free
deb-src http://repository.maemo.org/extras/ diablo free
deb http://repository.maemo.org/extras-devel/ diablo free non-free
deb-src http://repository.maemo.org/extras-devel/ diablo free" >> /etc/apt/sources.list</pre>

* Run these commands:
<pre>> apt-get update
> fakeroot apt-get install libqt4-gui
> fakeroot apt-get install libqt4-dev</pre>

* Do these steps for the DIABLO_X86 and the DIABLO_ARMEL target if you plan to build on both

===How to compile a Qt application in scratchbox===
All the Qt tools that you need are available in scratchbox. So in order to compile a Qt application you need to follow the
standard Qt way:
qmake -project
qmake file.pro
make

== [[Image:Hammer.png]] Porting a Qt application in Maemo ==

===Intro===
Porting a Qt Desktop application to Maemo requires very few efforts; This because the Maemo Qt libraries will take care of giving the Hildon Maemo look & Feel and enabling the hildon input method for your application.

===Overriding the Qt maemo changes===
====Maemo Style====
The Maemo style is the default style of the Qt applications that run in Maemo.
The other styles available in Qt 4.4 maemo are [http://doc.trolltech.com/4.4/gallery-cleanlooks.html QCleanLooks], [http://doc.trolltech.com/4.4/gallery-windows.html Windows] and [http://doc.trolltech.com/4.4/gallery-plastique.html Plastique] (It will be available in the next packages of Qt).

You can force your application to use another style in several way:

1. Running your application with the flag -style <style_name>
$> ./qt-test-application -style windows

HINT: You can put this flag in the Exec field of the desktop file that launch the application.

2. If you want to change your code, you can use this static function:[http://doc.trolltech.com/4.4/qapplication.html#setStyle QApplication::setStyle( QStyle * style )]

3. If you want to change the style only for a particular widget, you can call this function in the widget constructor: [http://doc.trolltech.com/4.4/qwidget.html#setStyle QWidget::setStyle( QStyle * style )]

====Showing the status bar====
The hildon applications don't have a stuatus bar. Qt for maemo hide the status bar by default.
You can show it again modifying your code.
TODO

===Adding Maemo changes to a Qt Application===
Some methods of Qt for Maemo are not available in the "standard" Qt libs.
Then a Qt application with specific Maemo Qt code can't be built outside the Maemo SDK.
To avoid this issue, the developer can use the preprocessor directives, for example:

#ifdef Q_WS_HILDON
//Specific hildon code here
#endif

===Limitations===
TODO

== [[Image:Bug.png]] Debugging a Qt application ==

===GDB ===
====Intro ====
The Gnu Project Debugger, or gdb for short, is a general purpose debugger that can be used for various debugging purposes.

====Debugging a Qt application into scratchbox====
TODO

====Debugging a Qt application into the device====
1. Installing gdb into the device
A. add the sdk tools repository to the catalogue list
B. install gdb by using apt-get (require around 6 Mb of space)

2. Install the debug symbols files in scratchbox (ARMEL target)
apt-get install libqt4-dbg

3. Run the application (device side)
$gdbserver 0.0.0.0:1234 ./qtApplication

4. Run the gdb client on your host PC (scratchbox side)
[sbox-DIABLO_ARMEL: ~/TEST/svn/qt4-x11-4.4.0/examples/widgets/tablet] > gdb ./qtApplication

5. Set the target of gdb
(gdb) target remote 172.21.37.117:1234

6. Tell to gdb to continue to debug the application on the device
(gdb) continue

7. Wait some moments...

8. Your application will appear on the device screen.

9. Happy debugging!

===Links===
[http://www.gnu.org/software/gdb/documentation/ GDB documentation & Tutorials]

[http://maemo.org/development/documentation/man_pages/gdbserver/ GDBServer man page]

[http://maemo.org/development/documentation/how-tos/3-x/maemo_debugging_guide.html maemo debugging guide]

[http://repository.maemo.org/pool/diablo/free/g/gdb/ gdb debian package for Diablo]

== [[Image:chart.png]] Profiling a Qt application ==
=== OProfile ===
Oprofile is a low overhead system-wide profiler for linux. It can be used to find CPU usage bottlenecks in the whole system and within processes. It works fine in the device, but viewing the reports can take quite a long time (10 minutes) when fired up on N800/N810 devices. Therefore, it often makes sense to run opreport in scratchbox.

If you want to know more about OProfile in Maemo click [http://maemo.org/development/tools/doc/chinook/oprofile/ here] to read a good how to.

=== Valgrind ===
TODO

== [[Image:package.png]] Packaging a Qt application for Maemo ==
[http://wiki.maemo.org/Packaging_a_Qt_application Find out more..]

== [[Image:Helmet.png]] Maemo Qt API Reference ==
Maemo Qt is based on Qt for X11. It shares the same API avoiding API breaks. In this way every Qt application that runs in other platforms (Windows, MacOS X, Linux, S60) can run also into the Maemo devices.

To Develop a Qt application you can use the [http://doc.trolltech.com/4.4/index.html Official Qt 4.4 API Documentation] and the list below to see what are the Maemo changes.

'''Double click radius'''
The application can set the double click radius by using:
static void QApplication::setDoubleClickRadius(int);
static int QApplication::doubleClickRadius();
The default value is 20px, usually you don't need to change it.

'''QTableEvents''' are able to get the pressure value from the touchscreen.
- The eventdeviceType is for the touchscreen is set to QTabletEvent::Stylus.

'''Finger poke''' is emulated in scratchbox by the Middle Mouse button (NOTE: There is no Fullscreen VKB in scratchbox)

'''QInputEvents''' don't move the cursor.
It's mandatory to get working the HIM moving the cursor via QInputMethodEvents.
Why is it mandatory?
Because if the user select text with the finger from the right to the left, we are able to remove the highlighted text, but the
cursor will be moved on the last char instead to stay on the first one.

To do that some changes has been added to some widget function like: ''widget::inputMethodEvent(QInputMethodEvent *e)''.
Modifing that function in some custom widgets may be necessary.
Don't reimplementing that function will break some fullscreen virtual keyboard features.

'''Hardcoded Keys:'''
In the QMainWindow:
- F6 - Toggle fullscreen the application
- F4 - Shows/Hides the application context menu
- Zoom in - is a standard [http://doc.trolltech.com/4.4/qkeysequence.html#StandardKey-enum key sequence] QKeySequence::ZoomIn
- Zoom out - is a standard [http://doc.trolltech.com/4.4/qkeysequence.html#StandardKey-enum key sequence] QKeySequence::ZoomOut

'''Input Method:'''
Maemo Qt uses the Hildon IM as default Input method.
Each kind of widget can set the IM mode. This allows the input method to focus on the type of input that the application is expecting.
Eg: spinboxes can receive only numeric characters (1-9).

NOTE: Qt widgets like QTextEdit, QLineEdit... set the right input method mode automatically.

A developer can change it by using:
void QInputContext::setInputMode(int mode);
It will update immediately the Hildon Input method to use the selected IM mode.

HIC Modes:
HILDON_GTK_INPUT_MODE_ALPHA alphabetical characters and whitespace
HILDON_GTK_INPUT_MODE_NUMERIC numbers 0-9 and the '-' character
HILDON_GTK_INPUT_MODE_SPECIAL special characters
HILDON_GTK_INPUT_MODE_HEXA hexadecimal characters; numbers 0-9, characters a-f, and A-F
HILDON_GTK_INPUT_MODE_TELE telephone numbers; numbers 0-9, whitespace, and the characters "pwPW/().-+*#?,"
HILDON_GTK_INPUT_MODE_FULL unrestricted entry mode, combination of the alpha, numeric and special modes.
HILDON_GTK_INPUT_MODE_MULTILINE the client contains multiple lines of text or accepts linebreaks in the input.
HILDON_GTK_INPUT_MODE_INVISIBLE do not echo or save the input in the IM when entering sensitive information such as passwords.
HILDON_GTK_INPUT_MODE_AUTOCAP automatically capitalize the first letter at the start of a sentence.
HILDON_GTK_INPUT_MODE_DICTIONARY enable predictive dictionaries and learning based on the input.

Example:
For a password field we need to set a specific IM mode:
int mode = HILDON_GTK_INPUT_MODE_FULL | HILDON_GTK_INPUT_MODE_INVISIBLE
QInputContext qic = widget->inputContext();
qic->setInputMode(mode);

If you are developing a Custom widget able to receive input text, you can instruct your widget to use the right IM Mode just returning
the mode.

- How does it work?
The Hildon IM sends a XMessage to pop up the "Virtual Keyboard" (or better the Main HIM UI) when an input widget receive the focus.
The IM before to raise the VKB, makes an inputMethodQuery to the widget retrieving the IM mode.
If the developer of the custom widget doesn't set the mode property, the IM will use HILDON_GTK_INPUT_MODE_FULL (the default mode) for that widget.

Setting the ImMode is quite easy. Check the code below for more understanding.

#ifdef Q_WS_HILDON
#include <QInputContext>
#endif

QVariant QAbstractSpinBox::inputMethodQuery(Qt::InputMethodQuery query) const
{
Q_D(const QAbstractSpinBox);
switch(query) {
case Qt::ImMode:{
int mode = HILDON_GTK_INPUT_MODE_NUMERIC;
return QVariant(mode);
}
default:
return d->edit->inputMethodQuery(query);
}
}

== [[Image:Helmet.png]] Contributing to the Maemo Qt Project ==
TODO

[[Category:Development]]
[[Category:Qt]]
[[Category:Development]]
[[Category:Qt]]